Of the estimated 55 million Pap smears performed each year in the United States, more than 5% are reported as abnormal (ALTS study 2003). An estimated 800,000 women each year present with low-grade squamous intraepithelial lesions (LSIL) (Jones, B A, Davey D D. Quality management in gynaecologic cytology using interlaboratory comparison. Arch. Pathol. Lab. Med. 2000; 124(5):672-81).
These lesions will either progress with time to cervical intraepithelial neoplasia (CIN) 2-3 or invasive cancer, especially in women that present with the high-risk HPV-subtype, or regress with time in the absence of treatment. Of women diagnosed with LSIL, 25% will progress to CIN grade 2 or 3, 22-32% will have persistent CIN 1 and approximately 50%-70% will experience spontaneous regression of LSIL within 2 years (ALTS group 2003; Östör A G, Natural history of cervical intraepithelial neoplasia: a critical review. Int. J. Gynecol. Pathol. 1993, 12:186-92). Approximately 75% will experience spontaneous regression within 5 years.
Previously, U.S. Ser. No. 12/532,752 disclosed biphasic compositions for treating women with human papilloma virus (HPV) presenting with LSIL. These compositions represented a first-in-class treatment protocol and show significant promise. These biphasic compositions employ interferon alpha-2b in an oil-in-water emulsion found in both intra-vesicular and extra-vesicular phases. The interferon in both phases is oxidatively stabilized by the addition of methionine which unexpectedly partitions preferentially into the aqueous portion of the emulsion.
While these compositions are in clinical trials, accelerated shelf-life studies show that a longer shelf-life would be beneficial. Accordingly, it would be desirable to provide for improved compositions having an extended shelf-life.